1. Field of the Invention
The present invention relates to a piezoelectric device including a thin film of a piezoelectric single crystal, and a production method for the piezoelectric device.
2. Description of the Related Art
In recent years, many piezoelectric devices in which a thin film of a piezoelectric single crystal is used have been developed. There is such a piezoelectric device which includes a piezoelectric thin film that functions as a piezoelectric device and having an electrode formed thereon; and a support that supports the piezoelectric thin film and in which a membrane structure forming a space between the support and a region where the electrode is formed is used (see, for example, Japanese Patent No. 4636292).
Japanese Patent No. 4636292 discloses a production method for a piezoelectric resonator having a membrane structure. In the production method disclosed in Japanese Patent No. 4636292, first, a sacrificial layer is formed on a front surface of a piezoelectric substance, and a support member is bonded to the front surface of the piezoelectric substance so as to cover the sacrificial layer. A piezoelectric film is peeled from the piezoelectric substance, and a so-called interdigital transducer (IDT) electrode and the like are formed on the piezoelectric film. Then, a through hole is formed in the piezoelectric film, and etching is performed through the through hole to remove the sacrificial layer. Accordingly, a piezoelectric resonator is produced in which the piezoelectric film is in a state of floating on a void.
In Japanese Patent No. 4636292, since the sacrificial layer is removed through the through hole formed in the piezoelectric film when forming the void, the through hole has to penetrate the piezoelectric film to reach the sacrificial layer. However, in the production method disclosed in Japanese Patent No. 4636292, it is difficult to determine whether the through hole formed in the piezoelectric film reaches the sacrificial layer. Thus, if the through hole does not reach the sacrificial layer, it may not be possible to remove the sacrificial layer by etching to form the void.